Well, I was in London last week (flying from Berlin). At both security checks, I put my watch in on of these robust cases for eyeglasses and put them deep into my rucksack. It's stupid to x-ray a watch, what kind a bomb should fit in there? However, my if the watch is buried in the bag it's more difficult to steale it.

Regarding the toilets, look out for lavatories... or try "where's the loo"?